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S142 cur ren t an thropology Volume 39 , Supplement, June 1998

change as forms of phenotypic adaptation to varying so- lutionary ecology, the issue of whether behavioral vari-ation is undirected with respect to adaptive valuecial and ecological conditions, using the assumption

that natural selection has designed organisms to re- (including the related issues of current versus future se-lective advantage and the explanatory role of inten-spond to local conditions in tness-enhancing ways.

Taking this assumption of adaptive design as a starting tions). Finally, we contrast the evolutionary archaeolog-ical approach to explaining archaeological change withpoint, evolutionary ecologists formulate and test formal

models incorporating specic optimization goals, cur- that of evolutionary ecology, using the origins of plant

domestication as a heuristic example. We concluderencies, and constraints.Judging from the virtual lack of cross-referencing in with a brief assessment of the archaeological promise ofeach approach.the literature, these two programs seem to view each

other as irrelevant at best and mutually exclusive oreven antagonistic at worst. How can it be that two pro-grams that derive from the same overarching theoreti-

What Is Evolving? Replicatorscal frameworkDarwinismarrive at such differentviews on how to describe and explain the archaeological and Phenotypesrecord? We argue that the primary conict between thetwo approaches centers on fundamental differences in In modern synthetic Darwinian theory, evolutionary

change proceeds through the action of natural selectionthe way they view the role of phenotypic variation, andin particular behavioral variation, in the evolutionary and other forces (e.g., mutation, drift) on genotypic vari-

ation and its phenotypic expression. Of these, only se-process. From these differences ow a series of conse-quences in explanatory scope, empirical application, lection produces cumulative, directional (nonrandom),

and creative evolution. As noted by Lewontin ( 1970)and theoretical conclusions. The aim of this paper is tooutline these differences and to evaluate the relative and many others (e.g., Dunnell 1980:38), in outline nat-

ural selection requires only three conditions: variation,utility of each approach for explaining archaeologicalphenomena. inheritance (transmission), and differential tness. But

because of the translation between genotype and pheno-Although the relationship between evolutionary ar-chaeology and evolutionary ecology may seem to be a typea process inextricably linked to environmental

and developmental factorsand the complexities of in-rather arid academic dispute turning on some esotericpoints of evolutionary theory, we feel that the implica- heritance wherever sexual reproduction is present, the

simplicity of evolution by natural selection is nestedtions for future research in archaeology and on culturechange generally are quite broad. If the proponents of within an extremely complex ontogenetic and popula-

tional context. Thus, a somewhat fuller outline of theevolutionary archaeology are correct, a clean sweep ofexisting paradigms in archaeology and even ethnogra- evolutionary process would be as follows: ( 1) genetic

variation is continually produced by mutation and re-phy is scientically warranted. Given the powerful,unifying role of Darwinian theory in the life sciences combination; ( 2) this variation interacts with external

environmental factors to shape phenotypes; ( 3) theseand the fractured state of theory in the social sciences,evolutionary archaeologys claim to the mantle of Dar- phenotypes and associated genotypes are differentially

successful in surviving and reproducing; ( 4) offspring in-winism comes at a signicant moment in the history ofanthropology. For this reason, we have endeavored to herit (some of) the genes and thus tend to develop the

associated phenotypes of their parents; ( 5) the prolifera-use the simplest, least ambiguous language possible inorder to make this critique accessible to a broad audi- tion of more successful genotypes results in transgener-

ational increase in phenotypes that are better adaptedence of professionals who may not have expertise in ar-chaeology or evolutionary theory. Of course, there are to local environments.

In adopting the Darwinian framework, evolutionaryother critiques of evolutionary archaeology in the re-cent literature (e.g., Schiffer 1996), but unlike these our archaeologists have simply substituted phenotypic vari-

ation for genetic, arguing that evolution by natural se-critique is rooted in an acceptance of the general Dar-winian framework; in other words, we locate the weak- lection applies to any population of entities character-

ized by heritable variation and differential replicationness of evolutionary archaeology in its awed grasp ofevolutionary biology rather than in its advocacy of Dar- success of the variants. They further argue that since

artifacts are a component of the human phenotype,winism per se.We begin with a brief outline of the fundamental changes in artifact frequencies through time can be ex-

plained by the same principles used in evolutionary bi-logic of natural selection, noting the critical distinctionbetween phenotypes (such as behavioral patterns) and ology, that is, the action of selection on phenotypic

variation. This position is clearly stated in various pas-replicators (such as genes). We argue that in many casesthe process that evolutionary archaeologists are calling sages (e.g., Leonard and Jones 1987:213; OBrien and

Holland 1992:37), including the following: Artifacts doselection is not selection at all but phenotypic adap-tation to environmental variation; we illustrate this not represent or reect something else that is amena-

ble to evolutionary theory; they are a part of the humanprocess using two examples from the archaeological andethnographic records. We then take up a central dis- phenotype. Consequently, artifact frequencies are expli-

cable by the same processes as those in biologyagreement between evolutionary archaeology and evo-


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b o o n e a n d s m i t h Critique of Evolutionary Archaeology S143

(Dunnell 1989:45). In this view, the forces or processes sary nor is a knowledge of the source of variability(Dunnell 1980:62).that give rise to phenotypic variation are unimportant

to the analysis of evolutionary change. All that matters In his recent paper entitled, provocatively enough,What Is It That Actually Evolves? Dunnell ( 1995) dis-is that variation have some heritable component and

that this variation have differential tness effects such cusses the possible evolutionary relationships betweenindividuals, species, assemblages, and societies butthat natural selection can occur. In evolutionary archae-

ological theory, the production of new phenotypic vari- never acknowledges the replicator-phenotype distinc-

tion or the issues raised by nonparental cultural trans-ation (including novel forms of behavior or artifacts) isseen as conceptually analogous to the process by which mission. This omission is striking given the central rolethat these matters have played in contemporary evolu-new variants arise in the genetic codeundirected mu-

tation and recombination. tionary theory in general and cultural evolutionary the-ory in particular (e.g., Dawkins 1976, Hamilton 1996,Although seemingly straightforward, this approach to

evolution by natural selection makes some very prob- Sober 1984, Trivers 1985, and Williams 1966 for biol-ogy; Boyd and Richerson 1985, Cavalli-Sforza and Feld-lematic assumptions. Foremost among these is the way

it handles the genotype-phenotype distinction. To be man 1981, Dennett 1996, and Durham 1991 for culturalevolution). By making artifacts the evolutionary unitsure, the heritability requirement does not specify that

inheritance be genetic; it could in principle be cultural subject to variation and selection, evolutionary archae-ologists are either ignoring the replicator-phenotype(the standard view in evolutionary archaeology). But se-

lection does require that there be replicators units of distinction and all its implications or proposing that ar-tifacts themselves are replicators; either position isheritable variation. As Dawkins ( 1978; 1982:81117)

and others (e.g., Hull 1980) have pointed out, replicators highly problematic.In biology, phenotypes are dened as the observablemust have certain causally signicant qualities: longev-

ity (they last for many generations), fecundity (they pro- result of the interaction between genotype and environ-ment (Mayr 1976:10) essentially all features of an or-duce copies of themselves), and copy delity (they are

replicated with near-perfect accuracy). Genes, con- ganism except its genes. Obviously, behavior is in-cluded in this encompassing denition, even behaviorsisting of DNA, and memes or culturgens (symboli-

cally or neurologically encoded information transmit- that is culturally transmitted. Evolutionary archaeolog-ical theorists have argued that artifacts, being theted via social learning) are the two most commonly

identied replicators. 2 equivalents of physical and behavioral traits (Leonardand Jones 1987:215), are what Dunnell ( 1989:44) hasThe particulate nature of inheritancethe crucial

fact that individuals (phenotypes, or vehicles, as colorfully termed the hard parts of the behavioral seg-ment of phenotypes. Recently, some evolutionary ar-Dawkins terms them) do not themselves replicate but

are dissolved each generationhas profound implica- chaeologists have employed Dawkinss ( 1978, 1982) no-tion of the extended phenotype as a justication fortions for evolutionary theory (e.g., Williams 1966, Daw-

kins 1982, Sterelny and Kitcher 1988). For one, it means viewing artifacts as phenotypic traits, arguing that justas biologists routinely include such things as spiderthat selection will generally design individuals to be-

have in ways that will lead to maximal representation webs and bird nests in their concept of phenotype, wesee no reason not to extend in similar fashion the no-of replicators in future generations. This in turn focuses

analytical attention on the relationships between repli- tion of the human phenotype to include such things asprojectile points and pottery, or . . . such artifacts as cer-cators, vehicles, and phenotypic traits; all these ele-

ments play crucial but quite distinctive roles in biologi- emonial architecture (OBrien and Holland 1995:181).But if behavior and its products (artifacts) are pheno-cal evolution.

How has evolutionary archaeology dealt with this typica position we agree withthen in order to applyDarwinian analysis to them we must determine whatcritical issue? According to Dunnell ( 1980:87), Perhaps

the most fundamental problem in developing evolu- replicators are associated with them. More fundamen-tal, Darwinian analysis must examine the ways intionary theory for cultural phenomena is the matter of

the unit of transmission. . . . Yet if evolutionary theory which phenotypic traits affect the replication success oftheir associated replicators. Since evolutionary archae-is to be applied in archaeology with any rigor at all, this

issue has to be addressed in concrete terms. Despite ology has failed to do so, there is no logical foundationfor Dunnells ( 1989:45) claim (quoted above) or the fol-this pronouncement, the mechanics of inheritance and

their critical consequences for the form that evolution- lowing: Since selection works on the phenotypethevehicle that carries and protects the germ-line repli-ary processes take have been virtually ignored in the

evolutionary archaeological literature (with the notable cators (the genes)then, with regard to humans, thosethings they manufacture and use to modify their envi-exception of Neiman 1995). Indeed, we are told that the

specic mechanisms of inheritance are irrelevant: ronment are subject to selection in the same way anysomatic feature is (OBrien and Holland 1995:181). Theknowledge of how inheritance is effected is not neces-problem with this conceptualization is that selectioncan act on phenotypic variation (e.g., artifact design and2. Other nominees for replicator status include immunological an-frequency) only to the extent that it is heritablethattigens (Burnet 1959, Ada and Nossal 1987) and neural circuits in

Edelmans ( 1987) neural Darwinism theory of learning. is, correlated with replicators transmitted from parent


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to offspring (or, in the case of cultural replicators, from traits or heritable variances of traits) is correspondinglygreat.model to recipient). The evolutionary archaeological

program assumes this correlation without further ex- Behavior is typically the most labile component of anorganisms phenotype. As contemporary evolutionaryamination and often without even articulating the as-

sumption. Furthermore, given that evolutionary archae- biologists see it, the evolutionary raison de tre of behav-ior is to allow organisms greater exibility in re-ology is positing cultural inheritance, its failure to pay

attention to the effect of cultural transmission path- sponding to variable environmental challenges in ways

that enhance survival and reproduction (Dawkins 1976:ways (e.g., parental versus nonparental, generationalversus peer-to-peer, one-to-many versus many-to-one) chap. 4; Pulliam and Dunford 1980: chaps. 13). In otherwords, behavioral plasticity allows organisms to adaptas well as secondary forces such as evolved preferences

is puzzling. Though its proponents often cite the theo- to changes in environmental conditions more rapidlythan they could through the process of selection actingretical literature on cultural evolution (e.g., Boyd and

Richerson 1985, Cavalli-Sforza and Feldman 1981, Dur- on genetic variation. Thus, even though this plasticityexacts tness costs (in terms of development, metabolicham 1991), they do not discuss the conclusion of this

theory that cultural transmission might sometimes pro- maintenance, and potential malfunction), in particularniches it more than repays these costs and hence hasduce evolutionary trajectories that differ radically from

those governing traits linked to Mendelian inheritance. evolved by natural selection.Evolutionary ecology generally analyzes phenotypicEvolutionary ecology takes a different and conceptu-

ally more complex but realistic view of phenotypic vari- variation in terms of adaptive strategiesthat is, asa series of tness-enhancing behavioral responses to dif-ation. It holds that organisms (including humans) have

been designed by selection to make extensive adaptive ferent environmental states (assuming that these stateshave been recurrent within the evolutionary history ofadjustments of their phenotypes. A nonbehavioral ex-

ample of this is the tanning response found in all but the organisms lineage and that the responses fallwithin its norm of reaction). This form of phenotypicthe darkest-skinned or albino people. Tanning is clearly

phenotypic variation, even when it involves historical, response is thus construed to be based on a set ofevolved decision rules (Krebs 1978 )geneticallyintergenerational change (e.g., a population that has

gone from working in the elds to working in factories evolved cognitive mechanisms that guide development,learning, problem solving, and stimulus response.and exhibits a diachronic shift in the frequency or in-

tensity of tanning). In the behavioral realm, this process Hence, in this view behavioral variation itself is not thedirect product of natural selection. Rather, selection en-of adaptive phenotypic variation involves the interac-

tion between genetically or culturally evolved cognitive ters the explanation only indirectly, as the process thatdesigned the behaving organism (or in fact its ancestors)mechanisms and variable environmental conditions.

Under this view, natural selections primary role lies in to respond facultatively and adaptively to particular en-vironmental conditions.accounting for these cognitive mechanismsthat is,

why they evolved and why they work the way they Most writers of both approaches seem to agree on thetheoretical importance of cultural transmission to andoand not in culling behavioral variation. Corre-

spondingly, environment plays a causal role in eliciting evolutionary understanding of historical change. For ex-ample, without it evolutionary archaeology could makephenotypic variation, not just a selective one after the

fact. In colloquial terms, the evolutionary ecological po- no claim that phenotypic variation is heritable, one ofthe three essential requirements of the theory of evolu-sition is nothing more than a claim that organisms have

problem-solving abilities at various levels (physiologi- tion by natural selection. At the same time, the two ap-proaches diverge in their treatment of phenotypic traits.cal, morphological, behavioral) and scales (short-term,

developmental, lifelong). Evolutionary archaeology treats these (especially arti-facts) as both vehicles (phenotypic) and replicators (di-A phenotypes tendency or capacity to respond differ-

entially to varying environmental conditions is called rectly subject to natural selection). In contrast, evolu-tionary ecology expects the transmission of culturalphenotypic plasticity (or lability). The phenotypic plas-

ticity of a given replicator (e.g., genotype) over a range of variants to be heavily inuenced by previously evolvedcognitive biases or decision rules. If the latter view isenvironmental conditions is termed its reaction norm

(Lewontin 1974:404; Stearns 1992:6165). In this correct, frequency changes in these variants over timemay be caused by factors other than concurrent naturalviewstandard within biology in general, including

evolutionary ecologyphenotypic variation that re- selection.sults from the interaction of genotype with environ-ment does not itself constitute evolutionary change,though an organisms capacity for adaptive phenotypic

Selection or Phenotypic Adaptation? Twoplasticity is an evolved trait shaped by natural selec-tion. If the phenotypes reaction norm is very broad, the Examples from the Archaeological Recordpotential for synchronic variation or diachronic changein the phenotype without any evolutionary change per Evolutionary ecologists and evolutionary archaeologists

seem to agree that natural selection is the primary ex-se (i.e., without changes in the frequency of heritable


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planatory mechanism in scientic evolution (Dunnell nisms of phenotypic adaptation privileged in evolution-ary ecology.1980:49). Selection operates as a mechanism or process

of evolutionary change in a population when some vari- Behavioral variation of the type just discussed willproduce corresponding variation in the kinds and fre-able heritable trait has correspondingly variable effects

on the tness of the individuals that inherit it. For ex- quencies of artifacts and ecofacts associated with thesebehaviors, including those which become part of the ar-ample, one major component of tness is the number

of offspring that survive to reproduce; parents that pro- chaeological record. Hence, the resulting variation and

directional change that we observe archaeologicallyduce more surviving offspring relative to others in thesame population are said to have higher reproductive cannot be assumed to have resulted from natural selec-tion acting on culturally transmitted variation; it couldsuccess. A heritable trait that causes its bearers to have

higher reproductive success than others in the popula- instead be the result of facultative behavioral strategiesthat are themselves the product of earlier evolutionarytion will increase in frequency within the population

over time. processes extending back thousands or millions ofyears. Thus, if we wish to explain variation in the ar-Evolutionary archaeologists have tended to consider

all directional phenotypic change through time as the chaeological record (or any other manifestation of hu-man behavior), we have at least two alternatives: weresult of natural selection acting directly on cultural

variation (Dunnell 1978). Yet most of the evolutionary can attribute this variation to the action of natural se-lection on adaptively random cultural variation (thearchaeological literature is quite unclear on the mecha-

nism(s) underlying selection. Some (e.g., OBrien and evolutionary archaeological program), or we can attrib-ute it to adaptive phenotypic variation (the evolution-Holland 1995:19091; Ramenofsky 1995:13539) sug-

gest that selection works via reproductive differences ary ecological program).In sum, analyzing synchronic variation or diachronicamong the individuals who utilize certain variable arti-

facts to interact with the environment. Others (e.g., change requires that we consider two distinct causalprocesses, one evolutionary and the other phenotypic.Leonard and Jones 1987:214; Jones, Leonard, and Abbott

1995:2829; Teltser 1995 a :56) argue that it is replica- Evolutionary ecologists tend to focus on strategic phe-notypic response and assume that the trait under studytive success of phenotypic traits (behavior or artifacts)

that matters, whether or not this is tied to reproductive has been designed by natural selection to have suf-cient phenotypic plasticity to track environmental vari-success. Sometimes this ambiguity concerning the

mechanism(s) of selection is directly indicated, as in ation optimally (i.e., in tness-maximizing ways).Hence, they do not equate phenotypic variation withJones et al.s (p. 26) reference to functional traits, and

the processes that inuence their differential survival, evolutionary change; instead, they attribute it toevolved capacities for adaptive variation (behavioral,collectively termed selection. Most selectionists sim-

ply avoid stating a position on the issue or do not rec- physiological, etc.). The evolutionary archaeologicalparadigm, in contrast, minimizes the role of phenotypicognize it as an issue. 3

In contrast, evolutionary ecology argues that selec- adaptation via decision making and ascribes adaptivechange to the action of natural selection on culturallytion acting on heritable variation is but one of several

processes by which changes in the frequency of pheno- inherited phenotypic variation. Neither view is likelyto be 100% correct, but we argue that the evolutionarytypic variants through time occurs. As we have sug-

gested, one of the most important of these processes is ecological approach is likely to explain a much largerproportion of the phenotypic change preserved in the ar-individual phenotypic variation in response to environ-

mental variation such as exogenous changes in prey chaeological and ethnographic records. We will now ex-amine this issue and illustrate these principles with ref-abundance, climate change, and the likein other

words, nongenetic adaptation to local (and locally vari- erence to two cases of historical change.able) conditions. Evolutionary ecology also proposesthat the aggregate consequences of individual pheno- the emergence of broad-spectrum foragingtypic adaptation can both change environmental con- in the archaicditionsas through increases in population density,resource depletion, habitat modication, or mate Our rst example concerns changes in prey choice that

are revealed in the archaeological record of the Northavailabilityand elicit new strategic phenotypic adap-tation to these altered conditions. Thus, quite complex American Archaic. This period is generally character-

ized by a major shift in hunting emphasis from large-and directional changes in phenotypic variation overhistorical time are expected to result from the mecha- bodied game to smaller prey and in many cases a greater

emphasis on gathering and processing of wild plantfoods (Bayham 1979). This trend has been closely docu-3. Recently, some evolutionary archaeologists (Jones, Leonard, and

Abbott 1995:28; Ramenofsky 1995) have suggested that nonran- mented in Central California by Broughton ( 1994); adom or directional frequency change of traits can also be due to parallel trend occurred in many regions of the Oldsorting (differential persistence of evolved lineages [Vrba and World during the Mesolithic. In the language of foragingGould 1986]) or some other type of correlation with traits undergo-

theory, the trend can be characterized in terms of an in-ing selection. To date, however, no publication has explored thearchaeological implications of this proposed mechanism. crease in diet breadth (Broughton 1994:501), wherein


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change in emphasis is dened as a process by which plements, and facilities for capturing, processing, andstoring the animal and plant foods that were added tohuman foragers broaden the range of prey taken by pro-

gressively adding lower-ranked (i.e., less efciently har- the diet. Since the techniques for making and usingsuch implements must have spread through some pro-vested) prey types to a previously narrower diet of

higher-ranked prey types (Smith 1983 a, Kaplan and Hill cess of cultural transmissionthat is, we do not imag-ine that each Archaic forager reinvented, say, the side-1992).

Why would humans expand their prey choice to in- notched point or seed-beater basketry as neededone

might argue that here is where evolutionary archaeolo-clude lower-ranked prey types? Broughton ( 1994, 1995)uses optimal foraging theory to generate a number of gys selectionist paradigm should come into full play.But again, we must keep in mind that natural selectionhypotheses about patterns of prehistoric prey choice in

Central California, including the central one that a de- acting on culturally transmitted variation is not neces-sarily the only or even the most important process re-cline in the abundance of more protable (higher-

ranked) large-bodied prey, such as artiodactyls (deer and sponsible for the spread of innovations and correspond-ing artifact frequency changes. From the evolutionaryelk) and sea otters, led to an expansion of the optimal

(and hence observed) diet to include more lower-ranked ecological perspective, adaptive phenotypic plasticity(decision making and selective imitation) is a moreprey such as shellsh, small game, and sh. Broughton

suggests that the per-capita decline in high-ranked prey plausible alternative.To illustrate this point we shift our attention to awas due to long-term increase in human population

density, but the optimal-prey-choice model would pre- more recent example of technological change in forag-ing strategies that allows us to examine the actual pro-dict the same broadening of the diet in the case of an-

thropogenic resource depletion. Climatic change may cess of change in more detail. In an article on NativeAmerican artifact replacement by European goods, Ra-also have been responsible for this decline in high-

ranked prey in some regions. menofsky (n.d.) posits that the rapid increase in Euro-pean horses in the 16th century and the Cree use ofWhatever the cause, foraging theory predicts that re-

duced encounter rates for higher-ranked resources will snowmobiles (Winterhalder 1980, 1981) are clear ex-amples of variants that increase due to selection (n.d.:eventually shift the optimal (efciency-maximizing)

diet breadth to include lower-ranked (higher-cost) re- 7, emphasis added). With respect to the Cree use ofsnowmobiles, we are in a good position to examine thissources (Charnov 1976, Stephens and Krebs 1986). This

is because the increased search time resulting from de- claim more closely.At the time of his eld study (which took place inclining encounter rates for high-ranked prey reduces the

overall return rate for specializing on such prey relative 1975), Winterhalder found that snowmobiles had comeinto general use among the Boreal Forest Cree, withto the returns that can be obtained from expanding the

diet to include lower-ranked but more frequently en- considerable effect on their foraging strategies. If Ra-menofskys claim that this process is due to selectioncountered prey types. 4 Thus, evolutionary ecology ex-

plains the trend toward broad-spectrum foraging in the rather than decision making is correct, we must imag-ine the following course of events to have occurred:Archaic in terms of the long-term aggregate conse-

quences of changing individual decisions of Archaic First, some Cree foragers adopted, for whatever reasons,the use of snowmobiles in hunting, while others contin-foragers in response to declining availability of large-

bodied animals. From this perspective, adaptive pheno- ued to walk to hunting sites on snowshoes. The snow-mobile users then experienced higher tness in thetypic exibility (decision making) is entirely sufcient

to explain the trend in question, and no appeal to selec- form of larger numbers of surviving offspring, perhapsbecause of greater foraging returns that could be used totion acting on cultural variation is necessary. Natural

selection is required only to explain why Archaic forag- feed more offspring or because of higher return ratesthat freed time to engage in other tness-increasing ac-ers (in common with human and nonhuman foragers

everywhere) have evolved the cognitive capabilities to tivities, such as mating, child care, and wage earning.Snowmobile use was then transmitted culturally to themake adaptive economic decisions.offspring of snowmobile adopters. Since hunting re-sources are ultimately limited, the resulting increase insnowmobiles in the subarctic snowmobile use eventually led to replacement of snow-shoe hunters by snowmobile users.The above example of adaptive change centered largely

around changes in resource choice. Of course, the Ar- Clearly, the process just outlined would be quiteslow, requiring many generations to result in the re-chaic and Mesolithic periods are also characterized by

the appearance and spread of a wide range of tools, im- placement of snowshoe hunting by snowmobiles, thenumber of generations depending upon the tness dif-

4. There are signicant complications involved in applying this ferential between snowmobile users and traditionaloptimal-prey-choice logic to central-place foragers utilizing multi- hunters. Yet Winterhalder ( 1981:88) reports that theple patches; these issues are reviewed in general terms by Stephens Cree adopted snowmobiles over the space of less thanand Krebs ( 1986), Smith ( 1991), and Kaplan and Hill ( 1992) and dis-

one human generation. Hence, it seems clear to us thatcussed in detail for the prehistoric California case by Broughton(1995). the rapid increase of snowmobile use, contra Ramenof-


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sky, cannot be due to the effect of natural selection act- evolved cognitive capabilities that allow them to per-ceive the relative efciency of different means (e.g.,ing on variation in locomotion techniques among the

Cree. snowmobiles versus snowshoes) for acquiring resourcesand to make decisions regarding adoption of new tech-Two objections to our argument might be raised at

this point. First, given the short time involved, one nology or patterns of behavior according to which willproduce the highest net gains. 5might question whether Ramenofsky really means that

natural selection is the process or mechanism responsi- We argue that adopting such an explanatory strategy

allows for a much richer analysis of change as well. Forble for the increase in the frequency of snowmobile use.Our interpretation that she does is bolstered by her re- example, Winterhalder argued that the Cree adoptedsnowmobiles because doing so increased foraging ef-cent discussion of the spread of the horse among his-

toric Plains Indians ( 1995:13839, emphasis added): ciency by reducing the amount of time it took to travelfrom settlements to hunting areas; in optimal foragingterms, snowmobiles decrease prey search time. UsingWithin 100 years of its introduction, the horse had

diffused as far east as Texas, north into Canada, and the optimal foraging framework allowed Winterhalderto make various predictions regarding changes in thesouth into Mexico (Ewers 1955). This rapidity sug-

gests that the horse was a functional trait that variety and range of prey taken upon encounter with theadoption of snowmobiles. Specically, an increase ingreatly increased the tness of individuals within

populations. The strength of the horse out-com- search efciency is predicted to result in a constrictionof the diet ( 1981:89); Cree hunters using motorizedpeted humans and dogs as a means of transport; the

speed of the horse gave it a unique advantage in transport should concentrate on more protable preysuch as moose and ignore lower-ranking prey withhunting. Consequently, individuals who owned

horses reproduced in greater numbers than others. lower return rates such as hare. As it turned out, Win-terhalder was able to conrm that Cree diet was broaderprior to the adoption of snowmobiles and outboards. WeClearly Ramenofsky sees the advantages of horses as

leading to their spread through natural selection (of cul- note that without the evolutionary ecological postulatethat evolved cognitive abilities allow foragers to weightural variation) rather than through adaptive decision

making, and since she has recently (n.d.) linked this the economic costs and benets of various tactics andstrategies and to choose the tactic or strategy that givescase with the Cree shift from snowshoes to snowmo-

biles and termed both the result of selection, we the highest energy return under the circumstances, theintimate strategic relationship between foraging tech-think our interpretation of what she means by selec-

tion is correct. nology and diet breadth would remain theoreticallyopaque.Second, one might question whether selection on

cultural variation must act through differences in bio-logical reproduction. As discussed in detail by cultural discriminating phenotypic fromevolution theorists (e.g., Cavalli-Sforza and Feldman evolutionary change1981, Boyd and Richerson 1985), since cultural inheri-tance is not limited to parent-offspring transmission, It might be argued that, if natural selection and adaptive

decision making have the same outcome (e.g., snowmo-the replication rate of memes need not be constrainedby the generation length of culture bearers. Thus, some bile adoption) and enhance tness in either case, it

doesnt matter whether we adopt the evolutionary ar-memes may spread horizontally (e.g., between peers)or even obliquely (from elders to various sets of non- chaeological or the evolutionary ecological explanation.

Now, it is true that adaptive decision making over adescendant juniors) in a rapid fashion more akin to epi-demics than to genetic inheritance. However, if (as in short time scale may produce results (including tness

effects) that are equivalent to the effect of natural selec-the example discussed here) the postulated evolution-ary mechanism is natural selection, then differential tion acting over longer time scales. This is largely be-

cause capabilities for phenotypic adaptation (includingtransmission requires heritable variation in individualsurvival and/or individual reproductive success, and adaptive decision making) are themselves the product

of past natural selection. However, this does not meantherefore generation length becomes an important rate-limiting constraint. The alternative that snowmobile that the two processes of adaptive change should bememes were transmitted more effectively than snow-shoe memes to nondescendant Cree (as well as off-

5. Just how detailed and ne-tuned these cognitive mechanisms arespring), while plausible, is not natural selection; more and how they are shaped by inheritance or learning are empiricalsignicant, it requires precisely the kind of adaptive de- matters that evolutionary ecologists are continually investigatingcision making that evolutionary archaeology is dedi- in humans and nonhumans. For example, how closely can people

or other organisms discriminate different mean rates of energycated to eliminating from archaeological explanation.gain, given variance in these rates over time? How extensively areHow, then, can we characterize this process of changeother components of tness (e.g., mortality risk) traded off againstwithin the framework of evolutionary theory? We resource capture rate? What are the relative roles of genetic and

would argue that increased snowmobile use is the result cultural inheritance in shaping these decision rules? We think itpremature to take strong positions on these issues.of the fact that Cree hunters, like all humans, inherit


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conated or that we can assume they will always pro- ance of individual behaviors, the same notionsshould allow us to predict mutations, a patentlyduce the same outcomes. The reasons for this have

some rather far-reaching implications for how we absurd notion.should view variation, selection, and evolutionary

This statement illustrates the reasoning by which thischange.approach rejects any explanatory paradigm which in-First, natural selection results in trait frequencycludes decision making or adaptive response. It is ulti-changes through time by favoring some variants and

mately based on the following logic:culling out others; the basis of this culling process is thedifferential success of replicators, generally via differen- 1. Darwinian evolution designs adaptationstial survival and fertility of organisms that exhibit the through the action of natural selection acting uponvariant traits and transmit the variant replicators un- heritable variation.dergoing selection. This means that the rapidity with 2. Through cultural transmission, phenotypic vari-which selection can act is signicantly constrained by ation (including behavior and artifacts) becomes heri-the generation span of the organism in question. Sec- table.ond, the strength of selection depends on ( 1) the amount 3. Undirected variation is an essential aspect of ge-of variation already existing in the population and netic evolution.(2) the degree of differential tness that the variant 4. Therefore, it is essential to cultural evolutiontraits confer on the individuals carrying themmathe- as well.matical features of natural selection enshrined in every

While we accept 13, we hold that 4 is a non sequitur.textbook on the subject. 6 In contrast, the rapidity withThe principle of undirected variation is certainly crit-which phenotypic response to changing environmental

ical to the theory of natural selection, for reasons statedconditions occurs is dependent not on the amount of clearly in the following passage (Rindos 1989 a :39):variation that already exists in a population but on therapidity with which environmental change is occurring. From the Darwinian perspective, undirected varia-Nor is the rapidity with which innovations can spread tion is important for its role in fueling the engine ofthough learning or cultural transmission necessarily de- evolutionary change by generating new forms whichpendent on the amount of preexisting phenotypic vari- may then be subject to selection. Indeed . . . with-ance. This is because innovations or variants can in- out a true concept of undirected variation, naturalcrease in frequency in a population not just through a selection is not only unnecessary but is actually im-culling process acting upon existing variation but be- possible. If variation is less than undirected, thencause they in some way satisfy evolved preferences or natural selection cannot be seen as a creative forcedecision rules better than do existing variants (Boyd and in evolution. . . . Only if we see variation as beingRicherson 1985:175). In other words, although traits produced randomly with respect to selective pres-adopted though social learning may well affect tness, sures may we claim that the directionality that maytheir increase or decrease in frequency through time is be observed in evolution over time is the result ofnot necessarily through the mechanism of differential natural selection.reproduction. We believe this point is critical for under-standing phenomena such as the adoption of horses or In the genetical theory of evolution by natural selec-

tion, the ultimate source of variation is mutation of thesnowmobiles.genetic code. This mutation process (along with othersources of genetic variation, such as recombination) isgenerally recognized to be undirected or random. WhatIs Behavioral Variation Analogousexactly does undirected or random mean here? Itto Mutation?means that the chance that a specic mutation will

the concept of undirected variation occur is not affected by how useful that mutation wouldbe (Futuyma 1986:76), where useful refers to effectsA central tenet of evolutionary archaeology is the ideaon the organisms survival and reproduction (i.e., tnessthat behavioral variation and innovation are undirectedvalue). For example, the probability that the mutationor independent with respect to selection. As Dunnellthat gives rise to the sickle cell trait will occur is com-(1980:62) succinctly puts it,pletely unaffected by the current prevalence of malaria.Selection determines which [behaviors] will be trans- Once the variant exists, the prevalence of malaria acts

mitted, not which will occur. Behavioral variability, as a selective factor determining its frequency in theno less than mutation in strictly biological settings, populations gene pool. The production of mutations isdoes not direct evolution. Selection acting on varia- undirected with respect to current selective advan-tion does. If inclusive tness or any other evolution- tage, and hence the production of novel variation in ge-ary concept would allow us to predict the appear- netical evolution is entirely independent of the current

selective advantage of new variants.The central issue at hand, then, is whether the gener-6. This relationship between the strength of selection and the

ation of behavioral variation is independent of selectiveamount of heritable variation also applies to cultural transmissionsystems (see Boyd and Richerson 1985: chap. 6). pressures (i.e., uncorrelated with adaptive benet) and


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hence conceptually analogous to mutation. We argue Cultural systems provide a wide array of variation gen-erating mechanisms, including rational decision mak-that it is not. While past selection does not determine

when, where, how, and why a particular mutation will ing, but none of these guide evolution over the longterm. That is accomplished by forces of selection andoccur, it does determine to a large extent when, where,

how, and why an organism will express a particular be- drift (p. 29, emphasis added). In a similar vein, Dunnell(1996 a :xi) states: We see ourselves as solving problemshavior (or other phenotypic state) in response to current

(or even projected) environmental conditions. Although and therefore rebel at the notion that the generation of

variation is random with respect to selective condi-mutations (with possible rare exceptions) are never sta-tistically directed in tness-enhancing directions, many tions. Yet there is absolutely no evidence that a La-marckian engine is at work in our evolution, since wespecies have evolved capabilities for phenotypic modi-

cation that are indeed directed towards tness en- have no access to future selective conditions. Whileadding the (questionable) label Lamarckian, thehancement. In the decision-rule paradigm of evolution-

ary ecology, these take the form under condition do thrust of this statement is the same as that of Jones etal.: human innovation is adaptively random because it x, but under condition do y (where x confers greater

tness benet than y under but less than y under ). does not anticipate future selective conditions. 8 Clearly,focusing on the unguided nature of cultural variationOf course, the directedness of behavioral innovation

is a matter of degree. We expect that behavioral innova- over the long term is a radical expansion of the origi-nal axiom of the genetic theory of evolution that muta-tion will sometimes be random with respect to tness

gain, particularly in novel ecological and social settings; tion is adaptively random with respect to current selec-tive conditions.the various problem-solving cognitive mechanisms (ra-

tional choice, scenario construction, etc.) are certainly While we certainly agree that neither behavioral vari-ants nor mutations can be determined or caused by fu-not omniscient. Even in these cases, however, we ex-

pect that genetically evolved learning mechanisms (e.g., ture selection or anything else that has not yet oc-curredcause must precede effect in any coherentoperant conditioning) will reshape behavior in tness-

enhancing directions within a relatively short time (i.e., causal accountthis is not a logical criticism of adapta-tionist or intentionalist accounts of cultural innova-less than the lifetime of an individual organism); after

all, this tness payoff is why selection designed these tion. The evolutionary archaeological argument followssupercially from the fact that the genetical theory ofmechanisms in the rst place. 7 Obviously, if we are cor-

rect about the generally adaptive nature of behavioral evolution by natural selection involves a two-step pro-cess: 1) the production of undirected variation andinnovation, this will often short-circuit the chance for

natural selection to alter the frequencies of such be- 2) the sorting of these traits by means of differential suc-cess of the variant forms over time (Rindos 1989 b :8).havior.We have argued above that what is true of genetic varia-tion is not necessarily true of cultural or behavioralthe future is now variation, but in any case the argument we are exploringhere is distinct in that it extends the axiom of undi-In arguing that behavioral or cultural innovations are

undirected with respect to selective pressures, some rected variation to refer to future selective pressures.Why would this extension be made? Although this isevolutionary archaeologists have in fact expanded the

original concept of undirected or adaptively random never fully spelled out, our best inference from the evo-lutionary archaeological literature and conversationsvariation to apply to both current and future selective

conditions (i.e., conditions that do not yet exist). For ex- with several key proponents is that it serves to protecttheir belief that behavioral innovation is analogous toample, Jones, Leonard, and Abbott ( 1995:18) state that

innovations arise independently of the processes of se- (undirected) mutation against attack on the groundsthat humans obviously do engage in directed pheno-lection. While the production of variants is to a degree

constrained by preceding states of the system, the na- typic (behavioral, technological, and cultural) innova-tion. Thus, the counterargument goes, even when suchture of that variation is not determined by the future

course of the system. By future course of the system innovations are consciously directed towards solvingcurrent adaptive problems, since no one can foresee fu-Jones et al. seem to mean future selective pressures, for

in the next few sentences they illustrate their point by ture environmental states or other changes in selectivepressures in the long run, behavioral variation is effec-arguing that many technologies have become far more

successful in contexts unrelated to ones for which they tively undirected.Our interpretation is supported by Neffs ( 1992:146)were intended originally (p. 18) and that neither indi-

viduals nor the systems they operated in could foresee claim that to direct evolution through innovation, hu-mans would have to solve future problems and exploitthe long string of events leading to the evolution of

agriculture. The summary statement of this paper is future opportunities, and would have to anticipate theimpact of particular solutions on conditions in the more

7. The literature on behavioral innovation and learning is of coursevast; for useful reviews of the relation between innovation and 8. We term the Lamarckian label questionable because Lamarck-

ian evolution posits that variation is responsive to present selectiveadaptive outcomes, see Boyd and Richerson ( 1985), Marler and Ter-race (1984), and Plotkin ( 1994). forces, not future ones.


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long-term future. This argument strikes us as faulty in Although we are skeptical that trade systems (particu-larly the ritualized forms that occur between sovereignthat it confuses the claim (of evolutionary ecology, for

example) that phenotypic innovation is often effec- polities like the Southeastern chiefdoms) require noforesight, we have no objection to the rest of Rindosstively directed at solving existing adaptive problems

and opportunities with the much stronger claim that it statement. But we do not see how these factors weakenexplanations based (in part) on adaptive decisions.is successful in anticipating changed adaptive condi-

tions in the future. In doing so, this argument holds While we grant that adaptive change often has many

unforeseen consequences, we wonder why this is anyphenotypic adaptation to a higher standard than naturalselection itself; to see this one can simply reword the more effective in emasculating the causal role of cul-tural innovation or behavioral adaptation than the samestatement by substituting adaptation for innova-

tion and natural selection for humans. 9 argument applied to natural selection. Surely overtime the selective pressures favoring any trait (such asHaving argued that innovation would have to be om-

niscient in order to be a signicant adaptive force, many domestication) will change as ecological and demo-graphic factors alter. In the same way, if behavioralevolutionary archaeologists conclude that most or all

directional change in human history must be due to se- responses to current adaptive problems ultimately al-ter the adaptive landscape (e.g., through populationlection. A particularly strong version of this view is that

all change is the result of selection acting upon the un- growth), new responses to the changed conditions canbe expected to arise. Only if the rate of environmentaldirected variant cultural forms existing at earlier points

in time (Rindos 1989 a :28). This logic is exemplied in change exceeds the capability for phenotypic adaptationor the changes are too subtle to be detected must wesome evolutionary archaeological discussions of domes-

tication, where the admission that people may engage assume that innovation is nonadaptive.A related critique of the evolutionary archaeologicalin incipient domestication in order to increase their

food supply or reduce risk is countered by arguing that position concerns its failure to recognize that humanshave highly developed and evolutionarily specializedin the long run this innovation will lead to resource spe-

cialization, population growth, and hence increased re- cognitive mechanisms for projecting past experienceinto the future and formulating behaviors that antici-source variability and nutritional risk. Such unintended

long-term consequences are then used to blunt the pate future environmental contingencies (Tooby andDeVore 1987; Byrne and Whiten 1988). This does notadaptive relevance of decisions and behavioral innova-

tions. mean that our explanations of such decision-making be-haviors locate the cause of the behavior in its actual fu-A striking example of this kind of argument occurs in

Rindoss ( 1989 a :33, emphasis added) discussion of the ture results, nor does it mean that strategic or decision-making models place their explanatory emphasis oneffect of maize production in the prehistoric American

Southeast: intended effects. According to evolutionary ecology,the causes of a behavioral strategy are to be located in

The most obvious way to deal with the interacting the interaction between an organisms evolved andfactors of increasing population, increasing potential learned cognitive and problem-solving capabilities andyield, and increased variance in that yield would be its current environmental conditions. Hence, cause pre-an attempt to buffer the system by increased associa- cedes behavioral effect, and a deterministic, evolution-tion and trade within and between regions. Then, if ary theory of behavioral variation is possible.a crop is bad in one locality, maize could be im- According to evolutionary archaeology, because peo-ported from other localities during the crisis period. ple cannot foresee future selective conditions or unin-This is a type of activity that requires no foresight, tended consequences of their actions, natural selectionmerely a response to a specic condition of immedi- ultimately determines cultural evolution, regardless ofate reduced food availability. Furthermore, over the short-term strategic adjustments people may con-time such arrangements could grow and have conse- sciously or unconsciously make to present conditions.quences that were totally unforeseeable at the mo- Thus, since organisms cannot foresee the changed se-ment that the exchange systems were initially estab- lective conditions of the future, their phenotypic re-lished. sponses are adaptively impotent and serve only as grist

for selections mill; all explanatory weight is carried byselection. Clearly this approach and evolutionary ecol-9. Neff ( 1992:146) in fact states the analogy to be that DNA mole-

cules know nothing of future evolutionary needs or opportunities. ogy have rather different views of the relation betweenThe same observation applies to humans who introduce innova- ecological and evolutionary time scales. Since evolu-tions to solve perceived problems or exploit perceived opportuni- tionary ecology assumes that selection has designed or-ties. But the analogy is faulty on two grounds. First, DNA mole-

ganisms to be able to solve most adaptive problems,cules can never know anything, and neither can naturalselection, whereas humans do have the cognitive capability to hypotheses guided by this assumption predict that peo-model future states of the world and the impact of those states on ple (and many other organisms) will be quite capable oftheir survival or other tness correlates with some degree of accu- responding to changed selective conditions with newracy. Second, as we are arguing here, the axiom of undirected varia-

adaptive strategies. Granted, a solution to one adaptivetion in Darwinian theory applies to the present adaptive value ofvariation, not any future adaptive value. problem may lead to the emergence of new problems,


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but this is just as true in the realm of natural selection cator) in any Darwinian sense. 10 Hence, environmentalchange, whether exogenous or anthropogenic, is not anas in that of behavioral problem solving. In the evolu-

tionary ecological view, the process is a recursive one evolutionary process. We argue that human history cancertainly be explained, at least in part, in terms of evo-whose causal structure can be diagrammed thus:lutionary processes, but evolutionary change and his-

current environmental conditions phenotypic adaptation torical change are not the same thing.

new phenotypic adaptation new environmental conditions intentions and causesThere is no nality or teleology to this view, just as A third way in which the selectionism of evolution-there is none if one substitutes evolutionary adapta- ary archaeology and the adaptationism of evolution-tion via natural selection for phenotypic adaptation. ary ecology may seem to diverge concerns the causalOf course, all behavioral strategies played out in the role of intentionality. Whereas evolutionary ecologicalpresent have some effect on future environmental theory and analysis often refer to decisions andstates. For example, in the case of diet-breadth expan- strategies and goals, a key programmatic elementsion discussed above, the successful foraging strategies of evolutionary archaeology is denial of the explanatoryof early Archaic hunters may have caused a reduction relevance of goals or intentions for evolutionary analy-in the abundance of large terrestrial mammals, to which sis. For example, OBrien and Holland ( 1990:44) contendlater Archaic foragers had to adjust. Such effects, com- thatmonly termed unintended consequences (i.e., effectsother than those sought by the decision-making organ- in one sense we can speak, rather trivially, of intentism), may constitute unselected consequences as

being a proximate cause of something, but of whatwellthat is, effects that alter the selective pressures analytical value is such a statement? Proximateimpinging on the behavioral strategies being analyzed. causes, in any scientic framework, are functionalExplaining unintended or unselected consequences, it causes, i.e. how things work. To invoke intent as anseems to us, is primarily a historical problem, not an explanation robs valid functional questions of theirevolutionary one. By this we mean that not all change interesting parts and replaces them with vitalistic,with observable material consequences (such as might directional components.show up in the archaeological record) is evolutionary

Similarly, Dunnell ( 1989:37) writes, If human inten-changedescent with modication caused by evolu-tions cause human history and diversity, then do wetionary mechanisms such as natural selection or drift.suppose that squirrel history and diversity, or oak treeWe suspect that much of the reason some evolution-history and diversity, or star history and diversity areary archaeological theorists emphasize future selec-the consequences of squirrel intentions, or oak tree in-tive conditions as an ultimate cause of change is theirtentions, or star intentions? Generally not. These phe-desire to make evolutionary theory a theory of unin-nomena are understood without recourse to vitalism.

tended consequencesthat is, a science of history (see We expect most behavioral ecologists to be in generalDunnell 1982). Rindos ( 1989 a :3839) provides one clearagreement with both of these statements. Let us bestatement of this view:careful, however, not to throw the baby out with thebathwater. Behavioral ecologists do not view behavioralViewing variation as undirected brings about avariants, strategies, or decisions as isomorphicchange in the way in which we set about at-with intentions. It is quite possible to talk about antempting to explain cultural evolution. Here, theoak speciess strategy for seed dispersal without assum-spread of behaviour throughout a society, or . . .ing that trees have actual intentions in dispersingthroughout the species, is the result of the tnessseeds. In general, evolutionary ecology employs suchinduced by that behaviour. . . . Rather than seeingstrategic language as a convenient shorthand, analyzingchange as a consequence of the adoption of a partic-adaptive design such as seed dispersal as if a plant hadular form of behaviour, emphasis is placed upon thedispersal intentions without assuming that it in facthistorical consequences of a particular variant formdoes. In the case of organisms that do seem to have in-of behaviour for the humans exhibiting that behav-tentions (such as humans), these are viewed as proxi-iour.mate causes in the manner suggested by OBrien and

Our main objection to this is simple. Unintended and Holland. Ultimately, such intentions are explained asunselected consequences take the form of environmen-tal effects as well as genetic and phenotypic ones. Some 10. In the case of coevolution between two or more populations (asenvironmental effects are caused by human agency, in predator-prey systems) or social interactions with tness conse-

quences within a population (as in mating systems or intraspecicwhile others, such as exogenous climate change, areresource competition), the relevant aspect of the environment fornot. With respect to phenotypic changes that result, theany player does contain replicators and hence is subject to evolu-distinction is not important, since humans must adjust tionary change. For that reason, evolutionary ecologists have

to these new conditions either way. What is important adopted special techniques such as evolutionarily-stable-strategytheory (e.g., Maynard Smith 1982) for analyzing such dynamics.is that the environment itself is not heritable (a repli-


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products of past (genetic or cultural) evolution; as Daly Begging the Meaningless Question:and Wilson aptly put it, natural selection has no goals, How Do We Explain Change?but it is the reason why organisms do ( 1991:219).Butand here is the nub of the dispute between the What can the evolutionary archaeological paradigmtwo approachesto the extent that intentions contrib- gain by viewing behavior as strategic problem solving?ute to phenotypic adaptation, they produce adaptive We would answer: a great deal of explanatory powerchanges without concurrent selection. that it currently lacks. Rindos ( 1984) eloquently charts

Many evolutionary archaeological theorists seem to the evolutionary effects of plant domestication butrecognize only two possibilities: either intentions ex- when considering why humans adopted domesticates inplain everything (the alleged conventional wisdom the rst place concludes that this is a question with-which they criticize) or they play only the minor sup- out meaning (p. 141). In the genetical theory of evolu-porting role of generating undirected variation. Thus, tion by natural selection, it may well be meaningless towe are told that for whatever reason, anthropologists ask why, say, the sickle cell trait arose in the rst place,are incapable of shrugging free of intention as the ulti- because the mutation which produced it presumablymate explanatory device (see Ramenofsky 1995). Inten- occurred independently of its benet to its heterozy-tion, however, explains nothing but how variation gous carrier (i.e., mutation is random with respect tomight be generated (OBrien and Holland 1995:180). adaptive value). Selection determines only the degree toHaving reduced intentionality to a black box that gener- which it would spread or persist in populations with aates variation, OBrien and Holland go on to undercut high incidence of malaria. It is, however, not meaning-even this role: This is not to say that intentions ex- less to ask why, for example, a forager faced with a se-plain the generation of variation, only that, like a host ries of options might decide to invest more time or en-of other agents, they can spawn variation. ergy in the propagation of plant foods. The distinction

What such pronouncements overlook is the critical turns once again on the issue of undirected variation.difference between positing intentions as the root cause Given what we know about mutations, the predictionof some phenomenon and positing them (or their func- that hemoglobin mutations are more likely to occur intional equivalent, such as the decision rules of evo- areas where malaria is endemic is sure to be incorrect,lutionary ecology or the cognitive algorithms of evo- but the prediction that foraging populations character-lutionary psychology) as intermediate links within a ized by sedentary settlement and resource intensica-causal pathway. Evolutionary archaeology rejects the tion are more likely to innovate by adopting cultigensrst position, and because it fails even to recognize the is plausible.second it considers the matter concluded. In contrast, Other applications of evolutionary archaeology ex-while sharing its rejection of intentions as root causes, hibit the same pattern of question-begging exempliedwe hold that evolutionary explanations of human his- by Rindos. Variation is notedpeople were planting atory and behavioral change generally need to include in- variety of crops, people were specializing or generaliz-tentions or their equivalent in the causal pathway being (Leonard 1989), people were living in larger andcause these often provide the link between natural smaller settlements, some people were organizingselection and behavioral regularities. That is, past ge- themselves into collective labor forces (Leonard andnetic (and perhaps cultural) evolution has shaped the Reid 1993 )but in each case the behavioral variationhuman psyche to be very effective at solving adaptive just happens to occur. The only opportunity for expla-problems, and one important element of the psyche is nation that remains is to make up plausible post hocwhat we commonly label intentions or goals or stories about why a given variant was selected for orpreferences. against. This procedure seems just as susceptible to the

We have pointed to both commonalities and differ- charges of circularity and storytelling that are leveledences between evolutionary ecology and evolutionary at many adaptationist explanations. Furthermore, thearchaeology. In contrast with evolutionary archaeology, post hoc nature of the selectionist explanation (i.e., theevolutionary ecology posits that humans have remark- evolutionary archaeological account of why the traitable capabilities to adapt their phenotypes to their envi- was selected for or against) virtually guarantees that itronments through learning and rational calculation. cannot be tested: it ultimately takes the form Such-The two approaches agree that we have the evolved ca- and-such was selected for because it was adaptive, andpacity for the cultural transmission of the phenotypes this is why.so acquired to the next generation. Taken together, this The prevalence of selectionist just-so stories in theadaptive dynamic resembles a Lamarckian process evolutionary archaeological literature has recently beenmore than a strictly Darwinian one (Boyd and Richer- recognized by at least some of its proponents, andson 1985, Gould 1979). Does this mean that we are sug- we cannot improve upon the following self-critiquegesting that evolution is directed by human strategic (OBrien and Holland 1995:188):responses to the environment, as Dunnell (quotedabove) implies? Not at all. As we have argued above, These just-so stories are neat little explanations

tethered loosely to evolutionary principles by thephenotypic adaptation in response to environmentalconditions does not cause change, it is change. unguarded use of the word selection. Measurable


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variation too often becomes prima facie evidence for domesticates; ( 2) the process is unintentional and re-sults from natural selection acting on adaptively ran-a groundless cause-and-effect relation between an ar-

tifact and some nebulous concept of tness and ad- dom variation in human behavior (culturally inherited)and domesticate morphology/physiology (geneticallyaptation. The terms selection, selective forces,

and selective agents become a ready means of un- inherited); ( 3) the result is generally symbiotic (enhanc-ing the tness of both parties) though not necessarilyderstanding patterns that emerge from our analysis

of data for which we have no other ready explana- stable; ( 4) domestication eventually leads to large in-

creases in human population density. Of these, only 2tion. is either controversial or truly novel; it is also the ele-In contrast, the evolutionary ecological research ment that places Rindoss account squarely within the

strategy is hypothetico-deductive, using explanatory evolutionary archaeological framework. In any case,models to develop testable predictions and then looking Rindos is at pains to differentiate his scenario fromfor evidence that bears on these predictions (Smith and more conventional ones in which humans intentionallyWinterhalder 1992 b ). Why were people planting things favor more productive plant varieties or engage in selec-rather than continuing to rely on wild foods? Why did tive breeding. As he puts it ( 1989 a :34), cultural pro-they do it where they did, when they did? Why were cesses such as innovation or discovery are processesthey generalizing or specializing? Why did large settle- that permit, but do not directly cause, cultural change.ments occur in some places and not others? Why did In the case [of domestication], the true reason for cul-people organize themselves into large labor forces in tural change may be detected only in the social and de-some places and not others? The logical structure of mographic consequences of agriculturally inducedevolutionary ecology seems to us to be uniquely suited changes in environment and behaviour. For purposesto answering these kinds of questions. Once we accept of this paper, then, it is critical to consider Rindossthat behavioral innovation is not adaptively random, claimso characteristic of evolutionary archaeologyoptimization models can be used to produce hypotheses that a true or valid explanation of domestication can-regarding which environmental factors are eliciting the not assign a causal role to behavioral innovation orvariation. And since these hypotheses typically incorpo- problem solving.rate specic ideas about the currency, constraints, and While a number of writers have discussed domestica-relevant environmental variables, they can be tested tion from an evolutionary ecological perspective (e.g.,empirically. 11 Structuring the problem in this manner Layton, Foley, and Williams 1991, Hawkes and OCon-allows one to suggest an answer to the meaningless nell 1992, Kaplan and Hill 1992, Redding 1988), the full-question posed by Rindos. est account is by Winterhalder and Goland ( 1993 and

Rindos ( 1980, 1984, 1989 a ) has been the primary evo- esp. 1997). As they put it, the microecological per-lutionary archaeological contributor to the literature on spective of optimal foraging theory can be used to ex-domestication. As he portrays it, domestication will oc- plain how low-ranked plant resources could have en-cur whenever certain ecological circumstances apply. tered the diet of hunter-gatherers, initiating theSpecically, when a foraging population modies the coevolutionary relationships which created domesti-environment so as to (unintentionally) enhance the dis- cates (Winterhalder and Goland 1997:32 ).persal, survival, or pollination of a plant population, The Winterhalder-Goland analysis relies primarily onthis modication will increase the food supply of the the prey-choice model discussed above. In this model,foragers and hence favor their behavioral patterns via prey (including protodomesticates) are ranked by theirnatural selection (of cultural variation). Domestication postencounter protability, which is independent ofensues when plant varieties that are genetically more their abundance or encounter rate. 12 Four categories ofsusceptible to human propagation and harvest are fa- protodomesticates are thus possible: protable/abun-vored through human-mediated natural selection. But, dant, protable/scarce, unprotable/abundant, andas Rindos notes, given the symbiotic and coevolu- unprotable/scarce. While Winterhalder and Golandtionary nature of this scenario, we could just as well say discuss scenarios involving each of these four possiblethat plants domesticate humans as the opposite. starting points, for brevity we will note only one, the

In outline, Rindoss analysis consists of four tenets: case of a protodomesticate that is unprotable (low-(1) domestication is fundamentally a coevolutionary ranked) but very abundant. As Winterhalder and Golandprocess that alters the traits of both domesticators and note, the prey-choice model predicts that such a re-

source will be ignored as long as higher-ranked prey are11. In optimization theory, currency refers to the variable thatis maximized by the optimal solution. In evolutionary ecology, cur-rencies, such as resource capture rate or predator detection rate, are 12. Protability here means expected net return (e.g., in calories)

per unit handling time, where handling is dened as pursuit, cap-usually proxies for tness, chosen because they are more readilymeasurable than tness itself. (For general discussions of opti- ture, and processing (i.e., any actions required to consume a re-

source once it is encountered). Protability is independent of en-mality modeling from this standpoint, see Krebs and Davies 1991,Maynard Smith 1978, Parker and Maynard Smith 1990, and Ste- counter rate whenever items are handled singly or in any other way

that does not create an economy of scale. For a detailed discussionphens and Krebs 1986; for applications to human behavior, seeSmith 1987, Smith and Winterhalder 1992 b, and various authors of these points, see Stephens and Krebs ( 1986: chaps. 2 and 3) or

Smith ( 1991:2049).in Smith and Winterhalder 1992 a. )


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sufciently abundant, but if such prey decline in abun- chaeological record. Since behavior is not empiricallyobservable in the archaeological record, the argumentdance (because of localized depletion, climate or habitat

change, human population growth, or any other reason), goes, we cannot study it there (e.g., Dunnell 1980:88;1989:43). Taken at face value, this sounds like a formthe protodomesticate will be incorporated into the diet.

Since in this case the protodomesticate is very abun- of radical empiricism, the tenet that science can onlyconsider directly observable phenomena. 14 Radical em-dant, the initial result will be a major infusion of food

energy into the population and a broadening of the diet piricism was once prevalent in a variety of sciences but

has been widely abandoned. Indeed, such a restriction(as all higher-ranked resources will continue to be takenwhenever encountered). The longer-term result will would eliminate much of nuclear physics, return psy-chology to 1950 s-era behaviorism, cripple historical ge-be massive ecological change, as human population

growth fueled by the protodomesticate produces deple- ology, and strip evolutionary paleontology to its (fossil-ized) bones. 15tion of many wild resources; there will also be nar-

rowing of the diet as the protodomesticate becomes It is characteristic of such radical empiricism that itis more readily advanced as a doctrine than adhered toever more protable and abundant by undergoing the

coevolutionary modications proposed by Rindos. in practice; archaeology is no exception. Perusal of theevolutionary archaeological literature reveals that vir-In their conclusions, Winterhalder and Goland dis-

cuss other approaches, including that of Rindos, and in tually the only cases in which changing artifact fre-quencies per se actually provide the empirical focus arefact show how an evolutionary ecological analysis can

be articulated with the evolutionary archaeological em- studies of stylistic variation (Neiman 1995 )whichevolutionary archaeologists have typically seen as re-phasis on unintended long-term consequences. Foraging

theory can be used to illuminate the role of various eco- sulting from drift, not selection. In any case, evolution-ary archaeologists are clearly interested in larger issueslogical circumstances in eliciting phenotypic responses

(behavioral innovations) that enhance forager tness as well. These include the origins of domestication,population aggregation and dispersal, collective labor,and have unintended but profound consequences for hu-

man population ecology. In providing the middle-range and the origins of complex societies.All of these topics involve whole suites of variable be-theory needed to connect selective pressures with be-

havioral responses, foraging theory can supply hypoth- haviors with which artifacts are only indirectly associ-ated. We do not empirically observe domestication be-eses on questions the Rindos model neglects: What cir-

cumstances led humans to select certain species for ing carried out in the archaeological record; rather, weobserve artifacts and ecofacts that we infer to be associ-exploitation? What are the economic and population

processes that accompany growing dependence on do- ated with domestication behavior. We do not observepeople aggregating or dispersing in the archaeologicalmesticates and cultivation? (Winterhalder and Goland

1997:127). This case suggests that the two approaches record, nor do we observe small independent socialgroups coalescing into larger sociopolitical units. Thecan be complementary rather than competitive, but this

complementarity requires an acknowledgment that de- archaeological record does not reveal humans exchang-ing goods or engaging in mobility or sedentism. Whatcisions and actions are fundamental to human (pheno-

typic) adaptation, not simply generators of adaptively we see are archaeological correlatesmaterial en-tailmentsof these various behaviors. Dunnells callrandom variation on which natural selection will then

act. 13 for archaeologists to abandon behavioral reconstruction(1989:45) has become a clarion call in evolutionary ar-chaeology; yet as soon as we utter words like settle-

What We See and What We Know: ment pattern we have already engaged in behavioralCan Archaeologists Study Behavior? reconstruction. Hence, Dunnells advice strikes us as

almost impossible to follow in practice. In our view, theIn addition to the theoretical issues discussed above, question of whether or not we can empirically study orthere is a more immediate and empirically based issuethat leads evolutionary archaeologists to reject a focus

14. This radical empiricism seems to have played a role in nar-on the analysis of behavior in archaeology. This is therowing the way some selectionists view evolution, as seen in theirview that archaeology should focus on changing artifact denition of evolution as consisting of the differential persistence

frequencies through time because these are the only of variation (e.g., Dunnell 1980:38; Jones, Leonard, and Abbottphenomena that are empirically observable in the ar- 1995:14; Ramenofsky 1995:135; Teltser 1995 a :4, 5). While such dif-

ferential persistence is certainly fundamental to evolution, the ex-planatory power of Darwinian theory comes from its success in ac-13. Signs of a move towards rapprochement with (or co-optation

of?) evolutionary ecology can be seen in recent suggestions that op- counting for the adaptive design of phenotypes and the creation ofnew designs. After all, Darwin made adaptive design and diver-timization analysis can play a valid role in evolutionary analysis.

For example, Jones, Leonard, and Abbott ( 1995:27) refer to engi- gence his central object of explanation and entitled his magnumopus The Origin of Species (not The Differential Persistence of neering criteria and adaptive optimization as powerful tools in un-

derstanding the selective processes acting through ecologic rela- Variants ).15. For a recent critical review of philosophical issues concerningtions that govern technologic change (see also Graves and

Ladefoged 1995; Maxwell 1995; OBrien and Holland 1995:190). observables in scientic explanation, explicating how and whyunobservable phenomena are necessary and proper elements of sci-Tellingly, though, only Graves and Ladefoged cite any of the abun-

dant evolutionary ecological literature on optimization analysis. entic investigation, see Kitcher ( 1993).


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infer behavior in the archaeological record is entirely through behavior. For one thing, geological or climaticfactors shaping taphonomic processes cannot them-one of degree and hence of considerably less metaphysi-

cal importance than some evolutionary archaeological selves evolve in any Darwinian sense. Teltsers sugges-tion that evolutionary archaeology must develop newtheorists (e.g., Dunnell 1989:43) would have us believe.

There is another strand to the rejection of behavioral theory to deal with behavior because evolutionary biol-ogy does not include the necessary terms to address be-reconstruction that turns on matters of explanatory

logic rather than empirical sufciency. This concerns havioral phenomena ( 1995 a :3) would be true only if

one ignored the explosion of theory and data developedthe idea that behavior has no lawfulness other than thatexternally imposed by selection. While we share evolu- in evolutionary behavioral ecology over the past threedecades (e.g., Alcock 1993, Krebs and Davies 1997). Un-tionary archaeologys skepticism concerning the induc-

tive epistemological strategy of behavioral archaeol- fortunately, evolutionary archaeology seems generallyto have done just that. As a result, it is just as vulnera-ogy (sensu Schiffer 1976), we share the latters view

that behavioral reconstruction of some sort is essential ble to the charge of parochialism and misinterpretationof Darwinism as it has shown midcentury cultural evo-to an understanding of large parts of the archaeological

record. In particular, we reject the view that the absence lutionism to be (Dunnell 1980, Leonard and Jones 1987).Ironically, the proposal to operationalize evolution-of behavior per se from the archaeological record makes

behavior an inappropriate object of archaeological ex- ary analysis strictly in terms of archaeologically ob-served phenomena brings its own intractable problemsplanation. We also reject the non sequitur that since be-

havior varies we cannot use it to explain the past, as in to the evolutionary archaeological program. This is par-ticularly clear in the way selectionists have attemptedthe following passage: There is no deterministic rela-

tion between the behavioral terms of reconstruction to operationalize the concept of selection in the analy-sis of archaeological change. Since selection is inargu-and the debris of the archaeological record. Such a rela-

tion would have to be founded in laws, and behavioral ably a dynamic process while the archaeological recordis essentially static (Binford 1983:1920), we cannot ac-laws, as just noted, cannot exist because behavior

changes. Without a deterministic relation between the tually observe selection occurring in the record anymore than we can observe behaviors. In a very inuen-two, behavioral explanations are untestable in the ar-

chaeological record (Dunnell 1992:216). That behavior tial article on patterns of artifact frequency change,Dunnell ( 1978) attempted to solve this problem by ar-changes does not make behavioral explanations un-

testable any more than changes in selective forces guing that any sustained directional change in the fre-quency of an artifact type is a sign of selection at work. 16make selectionist explanations untestable. Indeed, from

the evolutionary ecological perspective (as well as most But what might be true for genetic evolution and onpalaeontological time scales seems to us far more prob-of behavioral biology and social science), the regulari-

ties (deterministic relation) between behavior and the lematic in an archaeological or historical context. Thewell-documented secular trends of increased staturearchaeological record in fact derive from behavioral

change that responds to variation in social and natural and earlier age at menarche (Eveleth and Tanner 1990,Wood 1994), for instance, while quite directional andenvironments.

Furthermore, one does not have to adopt a law and sustained (having continued for centuries in some popu-lations) and of considerable magnitude (e.g., up to 30%order (Flannery 1973) view of behavior in order to posit

regularities between behavior and the archaeological reduction in menarcheal age in some populations),clearly result not from selection or any other form ofrecord. In fact, the evolutionary archaeological frame-

work only makes sense if there are regularities between evolutionary change but from phenotypic programs thatrespond to varying nutritional input with varyingenvironmental factors and archaeological change, regu-

larities which work via selection, drift, and other evolu- growth and maturation rates. A more archaeological ex-ample of the same process is the case of change in thetionary mechanisms. Evolutionary ecology adds the as-

sumption that regularities also are instantiated via character of the osteological remains in some stratiedsequence, the early occupants of a site or region havingphenotypic adaptation, including behavioral and tech-

nological responses. It also posits that many behavioral very robust skeletal structure while later occupants aremore gracile. Barring migration, this could be due toregularities (decision rules) are predictable because

these have been designed by past natural selection. evolution in robusticity (e.g., due to declining selectionpressure for channeling energy to bone growth or evenAs we argued above with respect to intentions, one

does not have to view behavioral factors as root causes to drift in a small population) or to phenotypic adjust-ments (maturing bones subject to less stress developof historical change to consider them important parts of

historical (including archaeological) explanation. While less robustly). The former change is evolutionary, whilethe latter is not. Or skeletal remains might show a dia-we recognize that because the archaeological record

does not provide any direct observational access to hu- chronic increase in signs of nutritional stress (e.g., Har-man behavior, the methods used in an evolutionary ar-chaeology will look very different than, for example, an

16. Dunnells argument has become a fundamental axiom in theevolutionary ethnography (Teltser 1995 a :3), we insist evolutionary archaeological literature; see, for example, Jones,that evolutionary explanations of the archaeological Leonard, and Abbott ( 1995), Neiman ( 1995), OBrien and Holland

(1990, 1992, 1995), among others.record must implicitly or explicitly trace causality


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ris lines); this again is phenotypic rather than evolution- Natural selection (and other evolutionary forces) mayshape behavioral variation in another way, through aary change. By positing natural selection as the only

source of sustained directional change, evolutionary ar- distinct process of c

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